30 



SOIL BACTERIOLOGY 



Exercise ii 



Effect of Season on Number of Bacteria 



1. In order to study the relation of bacteria to season, 

 select an isolated plot of soil high enough to prevent drain- 

 age from above. 



2. Draw samples of soil from this plot at intervals of 

 two weeks each during the fall and winter. If it is not 

 possible to make counts so often, plan to take samples 

 when there is a decided change in temperature If the 

 soil is frozen, it will be necessary to use a pick or hatchet 

 in securing samples 



Table 8 — Bfcct of Season on Niwibi? of Bacteria 



No 



Date 



Moisture 



Per cent 



Temperature of — 



Air 



Soil 



Bacteria per plate 



Average 



Bacterid m 

 I gm of 

 dry soil 



Average. 



